Piston



PISTON m O a g W W h M. a mm F i a Y w w fl fl ATTQRNEY.

March 30; 1937. P. KALB ET AL Filed Jan. 16, 1955 Patented Mar. 30, 1937UNITED STA'iE rarest OFFICE PISTON Application January 16, 1933, SerialNo. 651,996

Claims.

This invention relates to pistons for use in internal combustion enginesand has among its objects the provision of an improved pistonconstruction and method of making same.

5 A further object of our invention resides in the provision of a pistonof relatively light weight and having good heat conductive and wearingqualities. This invention combines in a novel way the desirablequalities of the present day aluminum pistons with the desirable wearingqualities of the cast iron piston.

In general, our invention consists in the provision of a piston havingan aluminum head and a cast iron skirt or cross-head portion, theseparts being connected in an improved manner whereby in operation underthe influence of heat, the piston will maintain its desired shape andother characteristics without warping and scufling.

A further feature of our invention resides in 3D the provision of anovel method of manufacturing a piston whereby the cooperating pistonparts are interconnected preferably by casting one into interengagedrelation with the other. In our preferred form the aluminum head is castin interengaging relationship with the cast iron skirt portion.

In carrying out our invention in the specific form illustrated, we haveprovided all contacts between the aluminum and cast iron in the form1:!) of frusto-conical surfaces whose apices lie at the intersection ofthe piston axis and the piston pin or boss axis. Thus, we have provideda contact between the head and skirt in the form of a frusto-conicalsurface whose apex lies at the in- 33 tersection of the piston and bossaxes, the axis of the cone lying along the piston axis.

The piston head is formed with bosses each having an inner cylindricalbore for receiving the usual piston pin. In order to prevent binding,

under heat expansion, at the bosses, we have formed a furtherfrusto-conical surface contact between the skirt and each boss, the apexthereof lying at the aforesaid intersection of the piston and boss axes.The axes of these cones lie along the boss or pin axes adjacent eachother.

By reason of the foregoing arrangement, all contacting surfaces betweenthe piston parts are subjected to sliding on each other, the expansion50 and contraction. taking place with respect to a common point wherebybinding tendencies are eliminated and the piston will, at all timesmaintain its desired cylindrical shape without diutortion heretoforeexperienced in composite 55 pistons.

Referring to the accompanying drawing which illustrates one embodimentof our invention,

Fig. 1 is a side elevation View of our piston, partly in cross-sectionto illustrate one of the bosses,

Fig. 2 is a side elevation View at right angles to that illustrated inFig. 1,

Fig. 3 is a section along the line 33 of Fig. 2, and

Fig. 4 is a sectional elevation view of the piston skirt, illustratingin dotted lines the manner of casting the head thereto.

Reference character A represents the piston assembly comprising ahead'structure H] and a skirt or cross-head structure H, the formerbeing of a relatively light weight material having goodheat conductivitysuch as the usual aluminum alloy ordinarily used in pistons for example,and the skirt 1 I being of a material having good wearing qualities.with the engine cylinder, such as cast iron for example. The head H)preferably has a diameter slightly less than skirt H, the latter havinga working fit with the cylinder and the head carrying the usual pistonrings (not shown) for holding the pressure and for carrying off heatfrom head it to the cylinder walls.

Head H) has depending therefrom, the arms l2 extending inwardly of theupper end of skirt II. Each arm i2 is provided with a laterallyextending boss I3, the bosses having piston pin-receiving bores I4,whose common axis l5 intersects the piston axis I6 at the point H. Wehave not shown the piston pin in the bores M as this 15 well known inthe art and forms no part of this invention per se.

Skirt H has diametrically opposite openings receiving the respectivebosses i3, these openings being in the form of a frusto-conical surfacel8, whose axis is the axis [5 aforesaid. The cones including surfaces l3are diagrammatically represented at x and m in Fig. 1, these coneshaving their apices at IT.

The upper end of skirt i l is formed with a circumferentially extendingfrusto-conical surface l9, whose axis is the axis l6 aforesaid. The coneincluding surface 49 is diagrammatically represented at y in Fig. 1,this cone having its apex at H.

We preferably form the head In by casting the aluminum (in a suitablemold) in the form shown whereby the head bosses l3 form companionfrusto-conical surfaces H8 in engagement with surfaces 58, and also thefrusto-conical annular surface it in engagement with surface [9. Thehead and skirt are thus interengaged or interlocked by thefrusto-conical surfaces and thereby held together. Furthermore, underheat variations, relative expansion and contraction between the head andskirt will take place by a sliding of surfaces l8, l8 and l9, IS in thedirection of the cones forming these surfaces, whereby binding ordistorting tendencies are eliminated.

It will be noted that we have a piston which is,

free from radially abutting surfaces which would 10 bind and causedistortion under heat; in our piston all abutting surfaces radially ofthe piston lie in cones as aforesaid whereby to permit free relativesliding without distortion.

We desire to point out that we do not limit our invention to theparticular arrangement of parts illustrated as various changes may bemade within the scope of our invention as defined by the appendedclaims. For example, the location of thelfrusto-conical surfaces axiallyof the piston is not important to a successful working of our invention,as long as these surfaces are parts of cones having apioes at a commonpoint, or approximately so, in keeping with the beneficial resultsdesired, While the best results of our invention are obtained bylocating this common point at the intersection of the pistonand. bossaxes, a shifting of this point within reasonable limits may, of course,be resorted to in keeping with the teachings of our invention. What weclaim as our invention is:

. 1. In a piston, a skirt structure formed with diametrically oppositeopenings bounded by frusto-conical surfaces respectively lying in a conewhose apex is located substantially at the 5 intersection of the pistonaxis and the axis of said openings, said skirt having an outercircumferential frusto-conical surface lying in a cone whose axissubstantially coincides with the piston axis and whose apex is locatedsubstantially at the intersection aforesaid, and a head structureprovided with bosses respectively extending into said skirt openings,said head structure having frusto-conical surfaces complementary to saidskirt surfaces and in sliding contact therewith. 2. In a piston, a skirtstructure formed with diametrically opposite openings bounded byfrusto-conical surfaces respectively lying in a cone whose apex islocated substantially at the intersection of the piston axis and theaxis of said openings, said skirt having an outer circumferentialfrusto-conical surface lying in a cone whose axis substantiallycoincides with the piston axis and whose apex is located substantiallyat the intersection aforesaid, and a head structure provided with bossesrespectively extending into the said skirt openings, said bosses havingfrusto-conical surfaces fitting within the surfaces of said skirtopenings respectively, said head structure having a frusto-conicalsurface engaging said circumferential frusto-conical surface of theskirt.

3. In a piston, a head structure, a skirt structure, one of saidstructures having a boss adapted to receive a piston pin, said bossshaving a frustoconical surface lying in a cone whose apex lies withinthe piston, and whose axis lies substantially along the axis of theboss,the otherof said structures having a surface complementary to saidfrusto-conical surface and in sliding contact therewith whereby relativetranverse movements due to expansion may freely takeplace.

between said structures without binding and dis! tortion thereof.

4. In a piston, a head structure, a skirt structure, one of saidstructures having'a boss adapted to receive a piston pin, saidbosshaving a frustoconical surface lying in a cone whose axis liessubstantially along the axis of the boss, the other of said structureshaving a surface complementary to said frusto-conical surface and insliding contact therewith, the apex of said cone lying substantially inthe axis of the piston.

5.'In a piston, an aluminum head structure formed with a lateral boss,and a cast iron skirt having an opening receiving the boss, said opening and boss having engaging frusto-conical relative sliding surfaceslying in cones having axes extending transverse to the piston, axis andtheir apices lying within the piston.

LEWIS. P. KALB. ANDRE J. MEYER.

